IPAC2015 - List of Keywords (betatron)

Paper	Title	Other Keywords	Page
MOPWA011	The Damping of Transverse Coherent Instabilities by Harmonic Cavities	synchrotron, simulation, damping, electron	102
	F.J. Cullinan, R. Nagaoka SOLEIL, Gif-sur-Yvette, France G. Skripka, P.F. Tavares MAX-lab, Lund, Sweden
	At nonzero chromaticity, the threshold current due to transverse coupled bunch instabilities in an electron storage ring is defined by intrabunch head-tail motion of higher than zeroth order. Multibunch tracking simulations predict that this threshold can be increased to several times its original value through the introduction of bunch lengthening harmonic cavities. One previously suggested explanation is the narrower spectra of the elongated bunches but reliable estimates for the threshold currents are not obtainable for anything other than rigid beam motion since the usual Sacherer formulism is not directly applicable to beams in a non-harmonic potential. A new scheme has been developed in which the decay time of a higher than zeroth order transverse head-tail mode may be estimated by taking into account the synchrotron tune spread generated by the harmonic cavity potential. This scheme is presented along with the results of numerical simulations performed in order to confirm the analytical predictions and justify the assumptions made. The extension of the scheme to more complex scenarios is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA011
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MOPWA024	Estimation of the Ion Density in Accelerators using the Beam Transfer Function Technique	ion, electron, synchrotron, impedance	147
	D. Sauerland, W. Hillert ELSA, Bonn, Germany A. Meseck HZB, Berlin, Germany
	Funding: Funded by the federal ministry of education and science of Germany The ELSA stretcher ring of Bonn University serves external hadron physics experiments with a quasi continuous electron beam of up to 3.2 GeV energy. Ions, being generated by collisions of the circulating electrons with the residual gas molecules, accumulate inside the beam potential, causing incoherent tune shifts and coherent beam instabilities. Detailed measurements were carried out in which ion dynamics is studied in dependence of beam energy and current, filling patterns and bias voltages of the ion clearing electrodes. By measuring the beam transfer function using a broadband transversal kicker, we were able to derive an estimate of the average ion density from the shift and broadening of the tune peak. In this contribution first results of these measurements are presented.
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MOPWA049	Simulation of Crab Waist Collisions in DAΦNE with KLOE-2 Interaction Region	simulation, luminosity, electron, detector	229
	M. Zobov, A. Drago, A. Gallo, C. Milardi INFN/LNF, Frascati (Roma), Italy D.N. Shatilov BINP SB RAS, Novosibirsk, Russia A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Research supported by DOE via the US-LARP program and by EU FP7 HiLumi LHC - Grant Agreement 284404. After the successful completion of the SIDDHARTA experiment run with crab waist collisions, the electron-positron collider DAΦNE has started routine operations for the KLOE-2 detector. The new interaction region also exploits the crab waist collision scheme, but features certain complications including the experimental detector solenoid, compensating anti-solenoids, and tilted quadrupole magnets. We have performed simulations of the beam-beam collisions in the collider taking into account the real DAΦNE nonlinear lattice. In particular, we have evaluated the effect of crab waist sextupoles and beam-beam interactions on the DAΦNE dynamical aperture and energy acceptance, and estimated the luminosity that can be potentially achieved with and without crab waist sextupoles in the present working conditions. A numerical analysis has been performed in order to propose possible steps for further luminosity increase in DAΦNE such as a better working point choice, crab sextupole strength optimization, correction of the phase advance between the sextupoles and the interaction region. The proposed change of the e^- ring working point was implemented and resulted in a significant performance increase.
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MOPJE052	Observations of an Anomalous Octupolar Resonance in the LHC	simulation, resonance, dipole, hadron	412
	F.S. Carlier, J.M. Coello de Portugal, A. Langner, E.H. Maclean, T. Persson, R. Tomás, R. Westenberger CERN, Geneva, Switzerland
	While linear LHC dynamics is mostly understood and under control, non-linear beam dynamics will play an increasingly important role in the challenging regimes of future LHC operation. In 2012, turn-by-turn measurements of large betatron excitations of LHC Beam 2 at injection energy were carried out. These measurements revealed an unexpectedly large spectral line in the horizontal motion with frequency Qx+2Qy. Detailed analyses and simulations are presented to unveil the nature of this spectral line.
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MOPJE054	Developments of the Segment-by-Segment Technique for Optics Corrections in the LHC	optics, simulation, coupling, quadrupole	419
	A. Langner, J.M. Coello de Portugal, P.K. Skowroński, R. Tomás CERN, Geneva, Switzerland
	Optics correction algorithms will become even more critical for the operation of the LHC at 6.5 TeV. For the computation of local corrections the segment-by-segment technique is used. We present improvements to this technique and an advanced error analysis, which increase the sensitivity for finding local corrections. Furthermore, we will investigate limitations of this method for lower beta-star optics as they will be used in the high-luminosity LHC (HL-LHC) upgrade.
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MOPJE057	Optics Measurement using the N-BPM Method for the ALBA Synchrotron	optics, quadrupole, dipole, synchrotron	430
	A. Langner, J.M. Coello de Portugal, R. Tomás CERN, Geneva, Switzerland G. Benedetti, M. Carlà, U. Iriso, Z. Martí ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The N-BPM method recently developed for the LHC has significantly improved the precision of optics measurements which are based on beam position monitor (BPM) turn-by-turn data. The main improvement is owed to the consideration of correlations for statistical and systematic error sources, as well as increasing the amount of BPM combinations for one measurement. We present how this technique can be applied at light sources like ALBA, and compare the results with other methods.
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MOPJE077	Progress on Simulation of Fixed Field Alternating Gradient Accelerators	simulation, closed-orbit, experiment, acceleration	495
	S.L. Sheehy JAI, Oxford, United Kingdom A. Adelmann PSI, Villigen PSI, Switzerland M. Haj Tahar, F. Méot BNL, Upton, Long Island, New York, USA Y. Ishi, Y. Kuriyama, Y. Mori, M. Sakamoto, T. Uesugi Kyoto University, Research Reactor Institute, Osaka, Japan D.J. Kelliher, S. Machida, C.R. Prior, C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Fixed Field Alternating Gradient accelerators have been realised in recent decades thanks partly to computational power, enabling detailed design and simulation prior to construction. We review the specific challenges of these machines and the range of different codes used to model them including ZGOUBI, OPAL and a number of in-house codes from different institutes. The current status of benchmarking between codes is presented and compared to the results of recent characterisation experiments with a 150 MeV FFAG at KURRI in Japan. Finally, we outline plans toward ever more realistic simulations including space charge, material interactions and more detailed models of various components.
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MOPMA041	Experimental Observation of Head-Tail Modes for Fermilab Booster	booster, linac, space-charge, dipole	636
	T. Zolkin University of Chicago, Chicago, Illinois, USA A.V. Burov, V.A. Lebedev Fermilab, Batavia, Illinois, USA
	The Fermilab Booster is known to suffer from beam transverse instabilities. An experimental attempt of head-tail modes extraction from the stable beam motion by periodic excitement of betatron motion has been performed. The shapes of head-tail modes have been successfully obtained while eigenfrequencies separation from the betatron tune were too small to be resolved. The qualitative agreement between the theory and an experimental data has been demonstrated. This is an important step towards the understanding of general theory of collective instabilities for strong space charge case, which is a rather typical case for hadron machines.
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MOPMA053	Characterizing Betatron Tune Knobs on Duke Storage Ring	wiggler, lattice, storage-ring, operation	672
	H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34-m long straight section of the storage ring can host up to four FEL wigglers in several different configurations. The storage ring magnetic lattice has designed with great flexibility to enable the operation with different wiggler configurations and at different electron beam energies. To realize smooth storage ring operation with various electron beam and wiggler parameters, a sophisticated lattice feedforward compensation scheme and a set of betatron tune knobs have been designed, developed and implemented in the controls system. The built-in compensation and tune knobs have demonstrated to be highly useful to allow transparent operation of the storage ring. To fully understand the effectiveness of the lattice tuning scheme, experiments have been carried to characterize the betatron tune knobs. In this paper, we will outline the measurement techniques and procedures, report experimental results, and make important observations on the usefulness of developing an advanced light source storage ring using accurate knowledge of individual magnets with high-quality measured fields.
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MOPMN008	Space Charge Studies in FFAG Using the Tracking Code Zgoubi	space-charge, emittance, simulation, damping	717
	M. Haj Tahar, F. Méot, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A method is implemented in Zgoubi that allows the computation of space charge effects in 2D distributions and with some restrictions in 3D distributions. It relies on decomposiing field maps or analytical elements into slices and applying a space charge kick to the particles. The aim of this study is to investigate the accuracy of this technique, its limitations/advantages by comparisons with other linear/nonlinear computation methods and codes, and to apply it to high power fixed field ring design studies.
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MOPMN016	Decoherence due to Second Order Chromaticity in the NSLS-II Storage Ring	synchrotron, storage-ring, damping, lattice	737
	G. Bassi, A. Blednykh, J. Choi, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	We study decoherence effects due to second order chromaticity for small amplitude kicks, in order to estimate the energy spread from TbT data of the NSLS-II storage ring. The bare lattice case (no Damping Wigglers and Insertion devices) has been considered, due to the long transverse radiation damping time. To minimize the chromatic damping/antidamping from the slow-head tail effect, we used a short train of bunches distributed over consecutive rf-buckets with a high enough average current to obtain a good BPM signal. The vertical and horizontal betatron motion have been excited independently with pinger magnets. In this contribution we limit the discussion to the horizontal case.
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MOPMN029	Spin Resonance Strength Calculation Through Single Particle Tracking for Rhic	resonance, proton, lattice, emittance	763
	Y. Luo, Y. Dutheil, H. Huang, F. Méot, V.H. Ranjbar BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with code DEPOL, which numerically integrate through the whole ring based on analytical approximate formula. In this article, we calculate the spin resonance strength by performing Fourier transformation to the actual transverse magnetic field seen by a single particle travelling through the ring. Comparison is made between the results from this method and DEPOL and other approaches.
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MOPHA031	Implementation of a Diagnostic Pulse for Beam Optics Stability Measurements at FLASH	kicker, optics, controls, diagnostics	850
	F. Mayet, R.W. Aßmann, S. Schreiber, M. Vogt DESY, Hamburg, Germany
	In order to monitor long-term stability of beam optics, simple and at the same time minimally invasive procedures are desirable. Using selectively kicked bunches, betatron phase advance, as well as potential growth of the betatron oscillation amplitude and the Twiss parameters alpha and beta can be extracted from BPM data. If done periodically, this data can be compiled into a long-term history that is accessible via the control system. This way it is possible to identify potential sources of beam optics errors. At FLASH the procedure could be implemented as a server/client tool. Since the whole procedure takes less than five seconds, operation is not disturbed significantly. In this work the possible implementation of the procedure is presented. It is also shown how the history data can be evaluated in order to infer possible beam optics error sources.
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MOPTY022	Bunch by Bunch DBPM Processor Development and Preliminary Experiment in SSRF*	injection, hardware, FPGA, experiment	984
	Y.B. Leng, Z.C. Chen, L.W. Lai, Y.B. Yan, Y. Yang SSRF, Shanghai, People's Republic of China
	Funding: Work supported by Chinese NSFC11375255. Digital BPM processor with turn-by-turn capability has been widely used in synchrotron radiation facilities over the world, which is proved to be very useful and powerful for daily operation and linear optics study but not good enough in the case of individual bunch information required. In order to sufficient individual bunch diagnostics requirements a development plan of the next generation DBPM processor with bunch-by-bunch capability has been initiated in SINAP since 2012. The whole development was divided into three steps: a concept processor based on digital oscilloscope IOC, an algorithm prototype processor based on commercial high speed ADC board, and a custom designed dedicated processor. The progress of this work and several preliminary beam experiments will be discussed in this paper.
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MOPTY065	Beam Stability of the Taiwan Light Source Storage Ring	storage-ring, electron, injection, network	1091
	H.C. Chen, H.H. Chen, Y.-S. Cheng, S.J. Huang, C.H. Kuo, J.A. Li, Y.K. Lin NSRRC, Hsinchu, Taiwan
	The Taiwan Light Source Storage Ring (SR) has been in operation since many years ago. Maintaining best stability of the electron beam is becoming the main challenge. This study endeavored to improve the electron beam stability of The Taiwan Light Source Storage Ring (SR). Employing the artificial neural network (ANN)-constructed experiment design to analyze and optimize the storage ring betatron tunes .This report outlines the details of the beam stability process experiment.
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MOPWI030	Low Emittance Tuning With a Witness Bunch	emittance, lattice, storage-ring, coupling	1223
	D. L. Rubin, R.E. Meller, J.P. Shanks Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by NSF PHY-1416318, PHY-0734867 and PHY-1002467, and DOE DE-FC02-08ER- 41538 and DE-SC0006505 Electron positron damping rings and colliders will require frequent tuning to maintain ultra-low vertical emittance. Emittance tuning begins with precision beam based measurement of lattice errors (orbit, transverse coupling, and dispersion) followed by compensation with corrector magnets. Traditional techniques for measuring lattice errors are incompatible with simultaneous operation of the storage ring as light source or damping ring. Dedicated machine time is required. The gated tune tracker (the device that drives the beam at the normal mode frequencies) and the bunch-by-bunch, turn-by-turn beam position monitor system developed at CESR are integrated to allow synchronous detection of phase. The system is capable of measuring lattice errors during routine operation. A single bunch at the end of a train of arbitrary length, is designated as the witness. The witness bunch alone is resonantly excited, and the phase and amplitude of the witness is mea- sured at each of the 100 beam position monitors. Lattice errors are extracted from the measurements. Corrections are then applied. The emittance of all of the bunches in the train is measured and the effectiveness of the correction procedure demonstrated.
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TUPWA019	A Canted Double Undulator System With a Wide Energy Range for EMIL	undulator, photon, optics, permanent-magnet	1442
	J. Bahrdt, H.-J. Bäcker, W. Frentrup, S. Gottschlich, C. Rethfeldt, M. Scheer, B. Schulz HZB, Berlin, Germany
	At BESSY II a canted double undulator system for the Energy Materials In-situ Laboratory EMIL is under construction. The energy regime is covered with two undulators, an APPLE II undulator for the soft and a cryogenic permanent magnet undulator CPMU17 for the hard photons. The layout and the performance of the undulators are discussed in detail. The minimum of the vertical betatron function is shifted to the center of the CPMU17. The neighboring quadrupoles and an additional quadrupole between the undulators control the vertical betatron function. Prior to the undulator installation a testing chamber with four movable scrapers has been implemented at the CPMU17 location. Utilizing the scrapers the new asymmetric lattice optics is tested and evaulated.
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TUPJE035	Optimization of Turn-by-Turn Measurements at Soleil and Alba Light Sources	quadrupole, lattice, synchrotron, storage-ring	1686
	M. Carlà, G. Benedetti, Z. Martí ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain L.S. Nadolski SOLEIL, Gif-sur-Yvette, France
	Turn-by-turn measurements paves the way for fast storage ring diagnostics. On the other hand turn-by-turn technique is by its very nature delicate, requiring an extensive system tuning and understanding. During last year several attempts to recover linear model informations from turn-by-turn measurements has been carried out in cooperation between the synchrotrons of SOLEIL and ALBA. A routine to extract phase advance and betatron amplitude from turn-by-turn measurements in presence of damping has been developed. Moreover a procedure to retrieve quadrupole errors from such observables has been developed tested and verified against the traditional diagnostics tools based on closed orbit measurements. A comparison between the different methods and the performance of the two different experimental setups are reported.
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TUPJE042	Transverse Tunes Determination from Mixed BPM Data	operation, storage-ring, injection, coupling	1709
	P. Zisopoulos, F. Antoniou, Y. Papaphilippou CERN, Geneva, Switzerland E. Hertle, A.-S. Müller KIT, Eggenstein-Leopoldshafen, Germany
	Decoherence due to non-zero chromaticity and/or amplitude dependent tune-shift, but also damping mechanisms can affect the accurate tune determination by leaving a limited number of turns for frequency analysis of the turn by turn (TbT) position data. In order to by-pass these problems, Fourier analysis of mixed TBT data from all BPMs can be employed. The approach is applied in two different accelerators, a hadron collider as the LHC and a synchrotron light source as the ANKA storage ring. The impact in the accuracy of the method of missing BPM data is also discussed.
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TUPMA053	Experience with First Turns Commissioning in NSLS-II Storage Ring	injection, kicker, storage-ring, lattice	1950
	S. Seletskiy, G. Bassi, J. Bengtsson, A. Blednykh, E.B. Blum, W.X. Cheng, J. Choi, R.P. Fliller, W. Guo, R. Heese, Y. Hidaka, S.L. Kramer, Y. Li, B. Podobedov, T.V. Shaftan, G.M. Wang, F.J. Willeke, L. Yang, X. Yang BNL, Upton, Long Island, New York, USA
	In this paper we describe our experience with commissioning of the first turns in the NSLS-II storage ring. We discuss the problems that we encountered and show how applying a dedicated first turns commissioning software allowed us to diagnose and resolve these problems.
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TUPHA004	NSLS-II Storage Ring Injection Optimization	injection, kicker, septum, timing	1968
	G.M. Wang, E.B. Blum, W.X. Cheng, J. Choi, Y. Li, S. Seletskiy, T.V. Shaftan, Y. Tian, L. Yang, L.-H. Yu BNL, Upton, Long Island, New York, USA
	The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. The SR is designed to work in top-off injection mode. The injection straight includes a septum and four fast kicker magnets with independent amplitude and timing control. The beam injection is designed as 9.5 mm off-axis in x plane and on-axis injection in y plane. To capture the injected beam within the SR acceptance for high injection efficiency, it requires 6-D phase space match. Besides that, the fast kickers formed local bump is also required to be locally to minimize the injected beam extra betatron oscillation and keep the stored beam disturbance within the specification, 10% beam size to minimize the injection transient. This paper will present the beam results before and after optimization.
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TUPHA009	NSLS-II Storage Ring Coupling Measurement and Correction	coupling, quadrupole, kicker, storage-ring	1983
	G.M. Wang, Y. Li, T.V. Shaftan, L. Yang, L.-H. Yu BNL, Upton, Long Island, New York, USA
	The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. To achieve the goal, 8 pm level vertical beam emittance, the coupling due to the misalignment in quads and vertical beam offset in sextuples must be corrected. Traditional method, based on response matrix, such as LOCO, is wildly used measure and corrects the coupling. In this paper, we present a new method to measure and correct the coupling with BPMs TBT data from fast kickers or pingers excited betatron oscillation. Besides the TBT data, other method, is also used to characterize the coupling.
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TUPHA013	Skew-Quad Parametric-Resonance Ionization Cooling: Theory and Modeling	coupling, resonance, emittance, focusing	1993
	A. Afanasev GWU, Washington, USA Y.S. Derbenev, V.S. Morozov, A.V. Sy JLab, Newport News, Virginia, USA R.P. Johnson Muons, Inc, Illinois, USA
	Funding: This work was supported in part by U.S. DOE STTR Grants DE-SC0005589 and DE-SC0007634. Muon beam ionization cooling is a key component for the next generation of high-luminosity muon colliders. To reach adequately high luminosity without excessively large muon intensities, it was proposed previously to combine ionization cooling with techniques using a parametric resonance (PIC). Practical implementation of PIC proposal is a subject of this report. We show that an addition of skew quadrupoles to a planar PIC channel gives enough flexibility in the design to avoid unwanted resonances, while meeting the requirements of radially-periodic beam focusing at ionization-cooling plates, large dynamic aperture and an oscillating dispersion needed for aberration corrections. Theoretical arguments are corroborated with models and a detailed numerical analysis, providing step-by-step guidance for the design of Skew-quad PIC (SPIC) beamline.
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TUPTY032	Study of Muon Backgrounds in the CLIC Beam Delivery System	shielding, collimation, hadron, background	2075
	F.B. Pilicer, E. Pilicer, I. Tapan UU, Bursa, Turkey H. Burkhardt, L. Gatignon, A. Latina, D. Schulte, R. Tomás CERN, Geneva, Switzerland
	We describe the detailed modelling of muon background generation and absorption in the CLIC beam delivery system. The majority of the background muons originates in the first stages of halo collimation. We also discuss options to use magnetised cylindrical iron shields to reduce the muon background flux reaching the detector region.
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TUPTY040	Comparison of Beam Sizes at the Collimator Locations from Measured Optics and Beam-based Collimator Alignment at the LHC	alignment, optics, injection, flattop	2101
	G. Valentino, R. Bruce, A. Langner, S. Redaelli, R. Tomás CERN, Geneva, Switzerland
	At the LHC, the collimation hierarchy is defined in units of the betatron beam size using the sizes at each collimator location. The beam size at a given collimator can be inferred from the gap measurement during beam-based alignment campaigns, when the collimator touches a reference beam halo defined with the primary collimators. On the other hand, the beta functions at each collimator are also measured as a part of the standard LHC optics validation. This paper presents a comparison of the beam size measurements at the collimator locations applying these two techniques for different machine configurations. This work aims at determining which is the most reliable method for setting the collimator gaps at the LHC.
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TUPTY066	Beam Cleaning in Experimental IRs in HL-LHC for Incoming Beam	collimation, optics, quadrupole, background	2181
	H. Garcia Morales Royal Holloway, University of London, Surrey, United Kingdom R. Bruce, S. Redaelli CERN, Geneva, Switzerland
	The HL-LHC will store 675 MJ of energy per beam, about 300 MJ more than the nominal LHC. Due to the increase in stored energy and a different interaction region (IR) optics design, the collimation system for the incoming beam must be revisited in order to avoid dangerous losses that could cause quenches and machine damage. This paper studies the ffectiveness of the current LHC collimation system in intercepting cleaning losses close to the experiments in the HL-LHC. The study reveals that additional tertiary collimators would be beneficial in order to protect not only the final focusing triplets but also the two quadrupoles further upstream.
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TUPTY069	Simulation of Hollow Electron Lenses as LHC Beam Halo Reducers using Merlin	electron, collimation, proton, simulation	2188
	H. Rafique, R.J. Barlow University of Huddersfield, Huddersfield, United Kingdom R.B. Appleby, S.C. Tygier UMAN, Manchester, United Kingdom R. Bruce, S. Redaelli CERN, Geneva, Switzerland
	Funding: Research supported by FP7 HiLumi LHC (Grant agreement 284404) The Large Hadron Collider (LHC) and its High Luminosity (HL) upgrade foresee unprecedented stored beam energies of up to 700 MJ. The collimation system is responsible for cleaning the beam halo and is vital for successful machine operation. Hollow electron lenses (HEL) are being considered for the LHC, based on Tevatron designs and operational experience, for active halo control. HELs can be used as soft scraper devices, and can operate close to the beam core without undergoing damage. We use the Merlin C++ accelerator libraries to implement a HEL and examine the effect on the beam halo for various test scenarios.
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TUPWI039	Modeling Crabbing Dynamics in an Electron-Ion Collider	electron, proton, collider, ion	2333
	A. Castilla, J.R. Delayen, T. Satogata ODU, Norfolk, Virginia, USA A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata JLab, Newport News, Virginia, USA A. Castilla DCI-UG, León, Mexico
	Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.
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TUPWI044	Final Muon Emittance Exchange in Vacuum for a Collider	quadrupole, emittance, collider, focusing	2346
	D.J. Summers, J.G. Acosta, L.M. Cremaldi, T.L. Hart, S.J. Oliveros, L.P. Perera, W. Wu UMiss, University, Mississippi, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by NSF Award 0969770 We outline a plan for final muon ionization cooling with quadrupole doublets focusing onto short absorbers followed by emittance exchange in vacuum to achieve the small transverse beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized xyz emittances of (0.071, 0.141, 2.4) mm-rad are exchanged into (0.025, 0.025, 70) mm-rad. Thin electrostatic septa efficiently slice the bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 microseconds, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87%.
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WEPJE015	Muon Tracking Studies in a Skew Parametric Resonance Ionization Cooling Channel	resonance, coupling, quadrupole, focusing	2705
	A.V. Sy, Y.S. Derbenev, V.S. Morozov JLab, Newport News, Virginia, USA A. Afanasev GWU, Washington, USA R.P. Johnson Muons, Inc, Illinois, USA
	Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0005589. This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Skew Parametric-resonance Ionization Cooling (SPIC) is an extension of the Parametric-resonance Ionization Cooling (PIC) framework that has previously been explored as the final 6D cooling stage of a high-luminosity muon collider. The addition of skew quadrupoles to the PIC magnetic focusing channel induces coupled dynamic behavior of the beam that is radially periodic. The periodicity of the radial motion allows for the avoidance of unwanted resonances in the horizontal and vertical transverse planes, while still providing periodic locations at which ionization cooling components can be implemented. A first practical implementation of the magnetic field components required in the SPIC channel is modeled in MADX. Dynamic features of the coupled correlated optics with and without induced parametric resonance are presented and discussed.
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THPF031	Towards an RF Wien-Filter for EDM Experiments at COSY	dipole, resonance, polarization, storage-ring	3761
	S. Mey, R. Gebel FZJ, Jülich, Germany
	Funding: The work is supported within the framework of the Helmholtz Association’s Accelerator Research and Development (ARD) program. The JEDI Collaboration (Jülich Electric Dipole Moment (EDM) Investigations) is developing tools for the measurement of permanent EDMs of charged, light hadrons in storage rings. The Standard Model predicts unobservably small values for the EDM, but a non-vanishing EDM can be detected by measuring a tiny build-up of vertical polarization in a beforehand horizontally polarized beam. This technique requires a spin tune modulation by an RF Dipole without any excitation of beam oscillations. In the course of 2014, a prototype RF ExB-Dipole has been successfully commissioned and tested. To determine the characteristics of the device, the force of a radial magnetic field is canceled out by a vertical electric one. In this configuration, the dipole fields form a Wien-Filter that directly rotates the particles' polarization vector. We verified that the device can be used to continuously flip the vertical polarization of a 970 MeV(c deuteron beam without exciting any coherent beam oscillations. For a first EDM Experiment, the RF ExB-Dipole in Wien-Filter Mode is going to be rotated by 90° around the beam axis and will be used for systematic investigations of sources for false EDM signals.
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Paper

Title

Other Keywords

Page

MOPWA011

The Damping of Transverse Coherent Instabilities by Harmonic Cavities

synchrotron, simulation, damping, electron

102

F.J. Cullinan, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
G. Skripka, P.F. Tavares
MAX-lab, Lund, Sweden

At nonzero chromaticity, the threshold current due to transverse coupled bunch instabilities in an electron storage ring is defined by intrabunch head-tail motion of higher than zeroth order. Multibunch tracking simulations predict that this threshold can be increased to several times its original value through the introduction of bunch lengthening harmonic cavities. One previously suggested explanation is the narrower spectra of the elongated bunches but reliable estimates for the threshold currents are not obtainable for anything other than rigid beam motion since the usual Sacherer formulism is not directly applicable to beams in a non-harmonic potential. A new scheme has been developed in which the decay time of a higher than zeroth order transverse head-tail mode may be estimated by taking into account the synchrotron tune spread generated by the harmonic cavity potential. This scheme is presented along with the results of numerical simulations performed in order to confirm the analytical predictions and justify the assumptions made. The extension of the scheme to more complex scenarios is also discussed.

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MOPWA024

Estimation of the Ion Density in Accelerators using the Beam Transfer Function Technique

ion, electron, synchrotron, impedance

147

D. Sauerland, W. Hillert
ELSA, Bonn, Germany
A. Meseck
HZB, Berlin, Germany

Funding: Funded by the federal ministry of education and science of Germany
The ELSA stretcher ring of Bonn University serves external hadron physics experiments with a quasi continuous electron beam of up to 3.2 GeV energy. Ions, being generated by collisions of the circulating electrons with the residual gas molecules, accumulate inside the beam potential, causing incoherent tune shifts and coherent beam instabilities. Detailed measurements were carried out in which ion dynamics is studied in dependence of beam energy and current, filling patterns and bias voltages of the ion clearing electrodes. By measuring the beam transfer function using a broadband transversal kicker, we were able to derive an estimate of the average ion density from the shift and broadening of the tune peak. In this contribution first results of these measurements are presented.

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MOPWA049

Simulation of Crab Waist Collisions in DAΦNE with KLOE-2 Interaction Region

simulation, luminosity, electron, detector

229

M. Zobov, A. Drago, A. Gallo, C. Milardi
INFN/LNF, Frascati (Roma), Italy
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia
A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Research supported by DOE via the US-LARP program and by EU FP7 HiLumi LHC - Grant Agreement 284404.
After the successful completion of the SIDDHARTA experiment run with crab waist collisions, the electron-positron collider DAΦNE has started routine operations for the KLOE-2 detector. The new interaction region also exploits the crab waist collision scheme, but features certain complications including the experimental detector solenoid, compensating anti-solenoids, and tilted quadrupole magnets. We have performed simulations of the beam-beam collisions in the collider taking into account the real DAΦNE nonlinear lattice. In particular, we have evaluated the effect of crab waist sextupoles and beam-beam interactions on the DAΦNE dynamical aperture and energy acceptance, and estimated the luminosity that can be potentially achieved with and without crab waist sextupoles in the present working conditions. A numerical analysis has been performed in order to propose possible steps for further luminosity increase in DAΦNE such as a better working point choice, crab sextupole strength optimization, correction of the phase advance between the sextupoles and the interaction region. The proposed change of the e^- ring working point was implemented and resulted in a significant performance increase.

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MOPJE052

Observations of an Anomalous Octupolar Resonance in the LHC

simulation, resonance, dipole, hadron

412

F.S. Carlier, J.M. Coello de Portugal, A. Langner, E.H. Maclean, T. Persson, R. Tomás, R. Westenberger
CERN, Geneva, Switzerland

While linear LHC dynamics is mostly understood and under control, non-linear beam dynamics will play an increasingly important role in the challenging regimes of future LHC operation. In 2012, turn-by-turn measurements of large betatron excitations of LHC Beam 2 at injection energy were carried out. These measurements revealed an unexpectedly large spectral line in the horizontal motion with frequency Qx+2Qy. Detailed analyses and simulations are presented to unveil the nature of this spectral line.

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MOPJE054

Developments of the Segment-by-Segment Technique for Optics Corrections in the LHC

optics, simulation, coupling, quadrupole

419

A. Langner, J.M. Coello de Portugal, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland

Optics correction algorithms will become even more critical for the operation of the LHC at 6.5 TeV. For the computation of local corrections the segment-by-segment technique is used. We present improvements to this technique and an advanced error analysis, which increase the sensitivity for finding local corrections. Furthermore, we will investigate limitations of this method for lower beta-star optics as they will be used in the high-luminosity LHC (HL-LHC) upgrade.

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MOPJE057

Optics Measurement using the N-BPM Method for the ALBA Synchrotron

optics, quadrupole, dipole, synchrotron

430

A. Langner, J.M. Coello de Portugal, R. Tomás
CERN, Geneva, Switzerland
G. Benedetti, M. Carlà, U. Iriso, Z. Martí
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The N-BPM method recently developed for the LHC has significantly improved the precision of optics measurements which are based on beam position monitor (BPM) turn-by-turn data. The main improvement is owed to the consideration of correlations for statistical and systematic error sources, as well as increasing the amount of BPM combinations for one measurement. We present how this technique can be applied at light sources like ALBA, and compare the results with other methods.

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MOPJE077

Progress on Simulation of Fixed Field Alternating Gradient Accelerators

simulation, closed-orbit, experiment, acceleration

495

S.L. Sheehy
JAI, Oxford, United Kingdom
A. Adelmann
PSI, Villigen PSI, Switzerland
M. Haj Tahar, F. Méot
BNL, Upton, Long Island, New York, USA
Y. Ishi, Y. Kuriyama, Y. Mori, M. Sakamoto, T. Uesugi
Kyoto University, Research Reactor Institute, Osaka, Japan
D.J. Kelliher, S. Machida, C.R. Prior, C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Fixed Field Alternating Gradient accelerators have been realised in recent decades thanks partly to computational power, enabling detailed design and simulation prior to construction. We review the specific challenges of these machines and the range of different codes used to model them including ZGOUBI, OPAL and a number of in-house codes from different institutes. The current status of benchmarking between codes is presented and compared to the results of recent characterisation experiments with a 150 MeV FFAG at KURRI in Japan. Finally, we outline plans toward ever more realistic simulations including space charge, material interactions and more detailed models of various components.

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MOPMA041

Experimental Observation of Head-Tail Modes for Fermilab Booster

booster, linac, space-charge, dipole

636

T. Zolkin
University of Chicago, Chicago, Illinois, USA
A.V. Burov, V.A. Lebedev
Fermilab, Batavia, Illinois, USA

The Fermilab Booster is known to suffer from beam transverse instabilities. An experimental attempt of head-tail modes extraction from the stable beam motion by periodic excitement of betatron motion has been performed. The shapes of head-tail modes have been successfully obtained while eigenfrequencies separation from the betatron tune were too small to be resolved. The qualitative agreement between the theory and an experimental data has been demonstrated. This is an important step towards the understanding of general theory of collective instabilities for strong space charge case, which is a rather typical case for hadron machines.

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MOPMA053

Characterizing Betatron Tune Knobs on Duke Storage Ring

wiggler, lattice, storage-ring, operation

672

H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34-m long straight section of the storage ring can host up to four FEL wigglers in several different configurations. The storage ring magnetic lattice has designed with great flexibility to enable the operation with different wiggler configurations and at different electron beam energies. To realize smooth storage ring operation with various electron beam and wiggler parameters, a sophisticated lattice feedforward compensation scheme and a set of betatron tune knobs have been designed, developed and implemented in the controls system. The built-in compensation and tune knobs have demonstrated to be highly useful to allow transparent operation of the storage ring. To fully understand the effectiveness of the lattice tuning scheme, experiments have been carried to characterize the betatron tune knobs. In this paper, we will outline the measurement techniques and procedures, report experimental results, and make important observations on the usefulness of developing an advanced light source storage ring using accurate knowledge of individual magnets with high-quality measured fields.

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MOPMN008

Space Charge Studies in FFAG Using the Tracking Code Zgoubi

space-charge, emittance, simulation, damping

717

M. Haj Tahar, F. Méot, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A method is implemented in Zgoubi that allows the computation of space charge effects in 2D distributions and with some restrictions in 3D distributions. It relies on decomposiing field maps or analytical elements into slices and applying a space charge kick to the particles. The aim of this study is to investigate the accuracy of this technique, its limitations/advantages by comparisons with other linear/nonlinear computation methods and codes, and to apply it to high power fixed field ring design studies.

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MOPMN016

Decoherence due to Second Order Chromaticity in the NSLS-II Storage Ring

synchrotron, storage-ring, damping, lattice

737

G. Bassi, A. Blednykh, J. Choi, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

We study decoherence effects due to second order chromaticity for small amplitude kicks, in order to estimate the energy spread from TbT data of the NSLS-II storage ring. The bare lattice case (no Damping Wigglers and Insertion devices) has been considered, due to the long transverse radiation damping time. To minimize the chromatic damping/antidamping from the slow-head tail effect, we used a short train of bunches distributed over consecutive rf-buckets with a high enough average current to obtain a good BPM signal. The vertical and horizontal betatron motion have been excited independently with pinger magnets. In this contribution we limit the discussion to the horizontal case.

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MOPMN029

Spin Resonance Strength Calculation Through Single Particle Tracking for Rhic

resonance, proton, lattice, emittance

763

Y. Luo, Y. Dutheil, H. Huang, F. Méot, V.H. Ranjbar
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with code DEPOL, which numerically integrate through the whole ring based on analytical approximate formula. In this article, we calculate the spin resonance strength by performing Fourier transformation to the actual transverse magnetic field seen by a single particle travelling through the ring. Comparison is made between the results from this method and DEPOL and other approaches.

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MOPHA031

Implementation of a Diagnostic Pulse for Beam Optics Stability Measurements at FLASH

kicker, optics, controls, diagnostics

850

F. Mayet, R.W. Aßmann, S. Schreiber, M. Vogt
DESY, Hamburg, Germany

In order to monitor long-term stability of beam optics, simple and at the same time minimally invasive procedures are desirable. Using selectively kicked bunches, betatron phase advance, as well as potential growth of the betatron oscillation amplitude and the Twiss parameters alpha and beta can be extracted from BPM data. If done periodically, this data can be compiled into a long-term history that is accessible via the control system. This way it is possible to identify potential sources of beam optics errors. At FLASH the procedure could be implemented as a server/client tool. Since the whole procedure takes less than five seconds, operation is not disturbed significantly. In this work the possible implementation of the procedure is presented. It is also shown how the history data can be evaluated in order to infer possible beam optics error sources.

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MOPTY022

Bunch by Bunch DBPM Processor Development and Preliminary Experiment in SSRF*

injection, hardware, FPGA, experiment

984

Y.B. Leng, Z.C. Chen, L.W. Lai, Y.B. Yan, Y. Yang
SSRF, Shanghai, People's Republic of China

Funding: Work supported by Chinese NSFC11375255.
Digital BPM processor with turn-by-turn capability has been widely used in synchrotron radiation facilities over the world, which is proved to be very useful and powerful for daily operation and linear optics study but not good enough in the case of individual bunch information required. In order to sufficient individual bunch diagnostics requirements a development plan of the next generation DBPM processor with bunch-by-bunch capability has been initiated in SINAP since 2012. The whole development was divided into three steps: a concept processor based on digital oscilloscope IOC, an algorithm prototype processor based on commercial high speed ADC board, and a custom designed dedicated processor. The progress of this work and several preliminary beam experiments will be discussed in this paper.

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MOPTY065

Beam Stability of the Taiwan Light Source Storage Ring

storage-ring, electron, injection, network

1091

H.C. Chen, H.H. Chen, Y.-S. Cheng, S.J. Huang, C.H. Kuo, J.A. Li, Y.K. Lin
NSRRC, Hsinchu, Taiwan

The Taiwan Light Source Storage Ring (SR) has been in operation since many years ago. Maintaining best stability of the electron beam is becoming the main challenge. This study endeavored to improve the electron beam stability of The Taiwan Light Source Storage Ring (SR). Employing the artificial neural network (ANN)-constructed experiment design to analyze and optimize the storage ring betatron tunes .This report outlines the details of the beam stability process experiment.

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MOPWI030

Low Emittance Tuning With a Witness Bunch

emittance, lattice, storage-ring, coupling

1223

D. L. Rubin, R.E. Meller, J.P. Shanks
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by NSF PHY-1416318, PHY-0734867 and PHY-1002467, and DOE DE-FC02-08ER- 41538 and DE-SC0006505
Electron positron damping rings and colliders will require frequent tuning to maintain ultra-low vertical emittance. Emittance tuning begins with precision beam based measurement of lattice errors (orbit, transverse coupling, and dispersion) followed by compensation with corrector magnets. Traditional techniques for measuring lattice errors are incompatible with simultaneous operation of the storage ring as light source or damping ring. Dedicated machine time is required. The gated tune tracker (the device that drives the beam at the normal mode frequencies) and the bunch-by-bunch, turn-by-turn beam position monitor system developed at CESR are integrated to allow synchronous detection of phase. The system is capable of measuring lattice errors during routine operation. A single bunch at the end of a train of arbitrary length, is designated as the witness. The witness bunch alone is resonantly excited, and the phase and amplitude of the witness is mea- sured at each of the 100 beam position monitors. Lattice errors are extracted from the measurements. Corrections are then applied. The emittance of all of the bunches in the train is measured and the effectiveness of the correction procedure demonstrated.

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TUPWA019

A Canted Double Undulator System With a Wide Energy Range for EMIL

undulator, photon, optics, permanent-magnet

1442

J. Bahrdt, H.-J. Bäcker, W. Frentrup, S. Gottschlich, C. Rethfeldt, M. Scheer, B. Schulz
HZB, Berlin, Germany

At BESSY II a canted double undulator system for the Energy Materials In-situ Laboratory EMIL is under construction. The energy regime is covered with two undulators, an APPLE II undulator for the soft and a cryogenic permanent magnet undulator CPMU17 for the hard photons. The layout and the performance of the undulators are discussed in detail. The minimum of the vertical betatron function is shifted to the center of the CPMU17. The neighboring quadrupoles and an additional quadrupole between the undulators control the vertical betatron function. Prior to the undulator installation a testing chamber with four movable scrapers has been implemented at the CPMU17 location. Utilizing the scrapers the new asymmetric lattice optics is tested and evaulated.

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TUPJE035

Optimization of Turn-by-Turn Measurements at Soleil and Alba Light Sources

quadrupole, lattice, synchrotron, storage-ring

1686

M. Carlà, G. Benedetti, Z. Martí
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
L.S. Nadolski
SOLEIL, Gif-sur-Yvette, France

Turn-by-turn measurements paves the way for fast storage ring diagnostics. On the other hand turn-by-turn technique is by its very nature delicate, requiring an extensive system tuning and understanding. During last year several attempts to recover linear model informations from turn-by-turn measurements has been carried out in cooperation between the synchrotrons of SOLEIL and ALBA. A routine to extract phase advance and betatron amplitude from turn-by-turn measurements in presence of damping has been developed. Moreover a procedure to retrieve quadrupole errors from such observables has been developed tested and verified against the traditional diagnostics tools based on closed orbit measurements. A comparison between the different methods and the performance of the two different experimental setups are reported.

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TUPJE042

Transverse Tunes Determination from Mixed BPM Data

operation, storage-ring, injection, coupling

1709

P. Zisopoulos, F. Antoniou, Y. Papaphilippou
CERN, Geneva, Switzerland
E. Hertle, A.-S. Müller
KIT, Eggenstein-Leopoldshafen, Germany

Decoherence due to non-zero chromaticity and/or amplitude dependent tune-shift, but also damping mechanisms can affect the accurate tune determination by leaving a limited number of turns for frequency analysis of the turn by turn (TbT) position data. In order to by-pass these problems, Fourier analysis of mixed TBT data from all BPMs can be employed. The approach is applied in two different accelerators, a hadron collider as the LHC and a synchrotron light source as the ANKA storage ring. The impact in the accuracy of the method of missing BPM data is also discussed.

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TUPMA053

Experience with First Turns Commissioning in NSLS-II Storage Ring

injection, kicker, storage-ring, lattice

1950

S. Seletskiy, G. Bassi, J. Bengtsson, A. Blednykh, E.B. Blum, W.X. Cheng, J. Choi, R.P. Fliller, W. Guo, R. Heese, Y. Hidaka, S.L. Kramer, Y. Li, B. Podobedov, T.V. Shaftan, G.M. Wang, F.J. Willeke, L. Yang, X. Yang
BNL, Upton, Long Island, New York, USA

In this paper we describe our experience with commissioning of the first turns in the NSLS-II storage ring. We discuss the problems that we encountered and show how applying a dedicated first turns commissioning software allowed us to diagnose and resolve these problems.

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TUPHA004

NSLS-II Storage Ring Injection Optimization

injection, kicker, septum, timing

1968

G.M. Wang, E.B. Blum, W.X. Cheng, J. Choi, Y. Li, S. Seletskiy, T.V. Shaftan, Y. Tian, L. Yang, L.-H. Yu
BNL, Upton, Long Island, New York, USA

The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. The SR is designed to work in top-off injection mode. The injection straight includes a septum and four fast kicker magnets with independent amplitude and timing control. The beam injection is designed as 9.5 mm off-axis in x plane and on-axis injection in y plane. To capture the injected beam within the SR acceptance for high injection efficiency, it requires 6-D phase space match. Besides that, the fast kickers formed local bump is also required to be locally to minimize the injected beam extra betatron oscillation and keep the stored beam disturbance within the specification, 10% beam size to minimize the injection transient. This paper will present the beam results before and after optimization.

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TUPHA009

NSLS-II Storage Ring Coupling Measurement and Correction

coupling, quadrupole, kicker, storage-ring

1983

G.M. Wang, Y. Li, T.V. Shaftan, L. Yang, L.-H. Yu
BNL, Upton, Long Island, New York, USA

The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. To achieve the goal, 8 pm level vertical beam emittance, the coupling due to the misalignment in quads and vertical beam offset in sextuples must be corrected. Traditional method, based on response matrix, such as LOCO, is wildly used measure and corrects the coupling. In this paper, we present a new method to measure and correct the coupling with BPMs TBT data from fast kickers or pingers excited betatron oscillation. Besides the TBT data, other method, is also used to characterize the coupling.

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TUPHA013

Skew-Quad Parametric-Resonance Ionization Cooling: Theory and Modeling

coupling, resonance, emittance, focusing

1993

A. Afanasev
GWU, Washington, USA
Y.S. Derbenev, V.S. Morozov, A.V. Sy
JLab, Newport News, Virginia, USA
R.P. Johnson
Muons, Inc, Illinois, USA

Funding: This work was supported in part by U.S. DOE STTR Grants DE-SC0005589 and DE-SC0007634.
Muon beam ionization cooling is a key component for the next generation of high-luminosity muon colliders. To reach adequately high luminosity without excessively large muon intensities, it was proposed previously to combine ionization cooling with techniques using a parametric resonance (PIC). Practical implementation of PIC proposal is a subject of this report. We show that an addition of skew quadrupoles to a planar PIC channel gives enough flexibility in the design to avoid unwanted resonances, while meeting the requirements of radially-periodic beam focusing at ionization-cooling plates, large dynamic aperture and an oscillating dispersion needed for aberration corrections. Theoretical arguments are corroborated with models and a detailed numerical analysis, providing step-by-step guidance for the design of Skew-quad PIC (SPIC) beamline.

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TUPTY032

Study of Muon Backgrounds in the CLIC Beam Delivery System

shielding, collimation, hadron, background

2075

F.B. Pilicer, E. Pilicer, I. Tapan
UU, Bursa, Turkey
H. Burkhardt, L. Gatignon, A. Latina, D. Schulte, R. Tomás
CERN, Geneva, Switzerland

We describe the detailed modelling of muon background generation and absorption in the CLIC beam delivery system. The majority of the background muons originates in the first stages of halo collimation. We also discuss options to use magnetised cylindrical iron shields to reduce the muon background flux reaching the detector region.

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TUPTY040

Comparison of Beam Sizes at the Collimator Locations from Measured Optics and Beam-based Collimator Alignment at the LHC

alignment, optics, injection, flattop

2101

G. Valentino, R. Bruce, A. Langner, S. Redaelli, R. Tomás
CERN, Geneva, Switzerland

At the LHC, the collimation hierarchy is defined in units of the betatron beam size using the sizes at each collimator location. The beam size at a given collimator can be inferred from the gap measurement during beam-based alignment campaigns, when the collimator touches a reference beam halo defined with the primary collimators. On the other hand, the beta functions at each collimator are also measured as a part of the standard LHC optics validation. This paper presents a comparison of the beam size measurements at the collimator locations applying these two techniques for different machine configurations. This work aims at determining which is the most reliable method for setting the collimator gaps at the LHC.

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TUPTY066

Beam Cleaning in Experimental IRs in HL-LHC for Incoming Beam

collimation, optics, quadrupole, background

2181

H. Garcia Morales
Royal Holloway, University of London, Surrey, United Kingdom
R. Bruce, S. Redaelli
CERN, Geneva, Switzerland

The HL-LHC will store 675 MJ of energy per beam, about 300 MJ more than the nominal LHC. Due to the increase in stored energy and a different interaction region (IR) optics design, the collimation system for the incoming beam must be revisited in order to avoid dangerous losses that could cause quenches and machine damage. This paper studies the ffectiveness of the current LHC collimation system in intercepting cleaning losses close to the experiments in the HL-LHC. The study reveals that additional tertiary collimators would be beneficial in order to protect not only the final focusing triplets but also the two quadrupoles further upstream.

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TUPTY069

Simulation of Hollow Electron Lenses as LHC Beam Halo Reducers using Merlin

electron, collimation, proton, simulation

2188

H. Rafique, R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom
R.B. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R. Bruce, S. Redaelli
CERN, Geneva, Switzerland

Funding: Research supported by FP7 HiLumi LHC (Grant agreement 284404)
The Large Hadron Collider (LHC) and its High Luminosity (HL) upgrade foresee unprecedented stored beam energies of up to 700 MJ. The collimation system is responsible for cleaning the beam halo and is vital for successful machine operation. Hollow electron lenses (HEL) are being considered for the LHC, based on Tevatron designs and operational experience, for active halo control. HELs can be used as soft scraper devices, and can operate close to the beam core without undergoing damage. We use the Merlin C++ accelerator libraries to implement a HEL and examine the effect on the beam halo for various test scenarios.

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TUPWI039

Modeling Crabbing Dynamics in an Electron-Ion Collider

electron, proton, collider, ion

2333

A. Castilla, J.R. Delayen, T. Satogata
ODU, Norfolk, Virginia, USA
A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA
A. Castilla
DCI-UG, León, Mexico

Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.

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TUPWI044

Final Muon Emittance Exchange in Vacuum for a Collider

quadrupole, emittance, collider, focusing

2346

D.J. Summers, J.G. Acosta, L.M. Cremaldi, T.L. Hart, S.J. Oliveros, L.P. Perera, W. Wu
UMiss, University, Mississippi, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

Funding: Work supported by NSF Award 0969770
We outline a plan for final muon ionization cooling with quadrupole doublets focusing onto short absorbers followed by emittance exchange in vacuum to achieve the small transverse beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized xyz emittances of (0.071, 0.141, 2.4) mm-rad are exchanged into (0.025, 0.025, 70) mm-rad. Thin electrostatic septa efficiently slice the bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 microseconds, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87%.

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WEPJE015

Muon Tracking Studies in a Skew Parametric Resonance Ionization Cooling Channel

resonance, coupling, quadrupole, focusing

2705

A.V. Sy, Y.S. Derbenev, V.S. Morozov
JLab, Newport News, Virginia, USA
A. Afanasev
GWU, Washington, USA
R.P. Johnson
Muons, Inc, Illinois, USA

Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0005589. This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Skew Parametric-resonance Ionization Cooling (SPIC) is an extension of the Parametric-resonance Ionization Cooling (PIC) framework that has previously been explored as the final 6D cooling stage of a high-luminosity muon collider. The addition of skew quadrupoles to the PIC magnetic focusing channel induces coupled dynamic behavior of the beam that is radially periodic. The periodicity of the radial motion allows for the avoidance of unwanted resonances in the horizontal and vertical transverse planes, while still providing periodic locations at which ionization cooling components can be implemented. A first practical implementation of the magnetic field components required in the SPIC channel is modeled in MADX. Dynamic features of the coupled correlated optics with and without induced parametric resonance are presented and discussed.

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THPF031

Towards an RF Wien-Filter for EDM Experiments at COSY

dipole, resonance, polarization, storage-ring

3761

S. Mey, R. Gebel
FZJ, Jülich, Germany

Funding: The work is supported within the framework of the Helmholtz Association’s Accelerator Research and Development (ARD) program.
The JEDI Collaboration (Jülich Electric Dipole Moment (EDM) Investigations) is developing tools for the measurement of permanent EDMs of charged, light hadrons in storage rings. The Standard Model predicts unobservably small values for the EDM, but a non-vanishing EDM can be detected by measuring a tiny build-up of vertical polarization in a beforehand horizontally polarized beam. This technique requires a spin tune modulation by an RF Dipole without any excitation of beam oscillations. In the course of 2014, a prototype RF ExB-Dipole has been successfully commissioned and tested. To determine the characteristics of the device, the force of a radial magnetic field is canceled out by a vertical electric one. In this configuration, the dipole fields form a Wien-Filter that directly rotates the particles' polarization vector. We verified that the device can be used to continuously flip the vertical polarization of a 970 MeV(c deuteron beam without exciting any coherent beam oscillations. For a first EDM Experiment, the RF ExB-Dipole in Wien-Filter Mode is going to be rotated by 90° around the beam axis and will be used for systematic investigations of sources for false EDM signals.

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